Objective To explore existing state and its pathology meanings of the two component circulating immune complexes of IgG specific activing complement(IgG/C\-3-TCIC) in patients with Graves' disease(GD).Methods By a capture ELISA,used coat IgG anti human C\-3 for coated antibody,HRP coat anti human IgG for second antibody,taking 219 cases of GD as a test group and 105 healthy individuals as a control one,IgG/C\-3-TCIC were characterized in this paper to compare its positive rate between the normal and abnormal levels of serum Ig,C\-3,T\-3,T\-4,FT\-3,FT\-4,TG,TM and different age,sex,and to analyse the correlation between IgG/C\-3-TCIC and serum total,free,composed Ig and C\-3.Results Both the levels and positive rates of IgG/C\-3-TCIC in GD patients were remarkably higher than those in the controls( P<0 01,0 001), its positive rates were no relations with age,sex and the levels of serum thyroxine,only notablely higher in the levels of serum IgA than those of the normal groups ( P<0 05) .IgG/C\-3-TCIC in GD patients only correlated with the complexed IgM( r=0 173 2,P<0 05) .In contrast,IgG/C\-3-TCIC correlated with total,free IgM and complexed C\-3( r=0 496 8,0 473 1,0 211 3,P<0 001,0 001,0 05) .Conclusion There were specific immune disorder in patients with Graves' disease.Ig switch had an important effect on regulating the formation of IgG/C\-3-TCIC.It cut a new approach to further illustrate the mechanism of the relational autoimmune diseases.